String template as argument to logging call

Reports string templates that are used as arguments to SLF4J and Log4j 2 logging methods. The method org.apache.logging.log4j.Logger.log() and its overloads are supported only for all log levels option. String templates are evaluated at runtime even when the logging message is not logged; this can negatively impact performance. It is recommended to use a parameterized log message instead, which will not be evaluated when logging is disabled.

Example (for Kotlin):

After the quick-fix is applied (for Kotlin):

Note that the suggested replacement might not be equivalent to the original code, for example, when string templates contain method calls or assignment expressions.

• Use the Warn on list to ignore certain higher logging levels. Higher logging levels may be always enabled, and the arguments will always be evaluated.

• Use the Do not warn when only expressions with primitive types, their wrappers or String are included option to ignore string templates, which contain only expressions with primitive types, their wrappers or String. For example, it could be useful to prevent loading lazy collections. Note that, creating string even only with expressions with primitive types, their wrappers or String at runtime can negatively impact performance.

New in 2023.1